Photonic Crystal Simulation

Photonic crystals are periodic structures that are designed to affect the motion of photons in a similar way that periodicity of a semiconductor crystal affects the motion of electrons. The non-existence of propagating EM modes inside the structures at certain frequencies introduces unique optical phenomena such as low-loss-waveguides, omni-directional mirrors and others. The part of the spectrum for which wave propagation is not possible is called the optical band-gap.  The underlying physical phenomenon is based on diffraction. Therefore, the lattice constant of the photonic crystal structure has to be in the same length-scale as half the wavelength of the electromagnetic wave. Figure 1 shows a one dimensional periodic structure which is investigated by using the transient solver of CST MICROWAVE STUDIO® (CST MWS).

1 dimensional periodic structure
Figure 1: 1 dimensional periodic structure

The rods are made from GaAS with refractive index of 3.4 and with an edge length of about 180 nm. The lattice spacing between the rods is 760 nm. As a first step, the transmission of a plane wave through this crystal is simulated.

single column of the array
Figure 2: single column of the array

By using appropriate boundary and symmetry conditions it is sufficient to calculate a single column of this array as shown in Figure 2. In this case, the structure is driven by a waveguide port. Due to the magnetic and electric symmetry planes, the excitation mode is a  normally incident plane wave.

Transmisson vs. wavelength
Figure 3: Transmisson vs. wavelength

Figure 3 shows the transmission through the structure. Between 1400 and 2200 nm the transmission is zero. In this bandgap region no wave propagation in possible.

Wave Propagation at frequencies below the band gap
Figure 4: Wave Propagation at frequencies below the band gap

Figures 4-6 shows the propagation of a plane wave at normal incident for at different frequencies.

Wave propagation at frequencies in the band gap
Figure 5: Wave propagation at frequencies in the band gap

Wave Propagation at frequencies above the band gap
Figure 6: Wave Propagation at frequencies above the band gap

The information obtained about the photonic band gap can be used to design optical devices. Figure 7 shows the periodic PBG structure as described above. A line defect is introduced and the structure is excited with a electromagnetic wave at band gap frequencies. The wave can only propagate inside the line defect.

Photonic Crystal with line defect
Figure 7: Photonic Crystal with line defect

Finally, Figure 8 shows the wave propagation inside the Photonic crystal with a bent defect. Again, the structure is driven with a time harmonic signal. The signal frequency is inside band gap of the crystal. Consequently, the wave propagates inside bend defect.

Photonic crystal with a bend defect
Figure 8: Photonic crystal with a bend defect

This article demonstrates the possibilities to model photonic crystals with CST MWS by using the transient solver. The general characterization would also be possible with the Frequency Domain and Eigenmode Solver of CST MWS by applying periodic boundary conditions.

CST Article "Photonic Crystal Simulation"
last modified 15. Jan 2007 5:42
printed 23. Apr 2014 8:19, Article ID 296

All rights reserved.
Without prior written permission of CST, no part of this publication may be reproduced by any method, be stored or transferred into an electronic data processing system, neither mechanical or by any other method.


5 of 11 people found this article useful

Did you find this article useful?

Other Articles

Analyzing Power Integrity Issues from Power Plane Interactions

Analyzing Power Integrity Issues from Power Plane Interactions Document type
When a printed circuit board (PCB) includes a power plane that is near to signal traces or other power planes, there is a significant risk of energy transfer between parts of the system. Not only does this coupling lead to power switching noise being transferred into data signals, it also means that power supply systems may demonstrate additional resonances that are not seen in the individual components. This can affect the power integrity of the PCB and may reduce its speed or reliability. This paper will explore some of the potential power integrity issues that can affect a PCB and explain how simulation can be used to help reduce these effects. Read full article..

Electromagnetic simulation of a low voltage industrial circuit breaker

Electromagnetic simulation of a low voltage industrial circuit breaker
This article demonstrates the workflow for the CST EM STUDIO® (CST EMS) electromagnetic simulation of a circuit breaker in domestic and industrial applications. A CATIA model is imported and parameters attributed to moving parts to facilitate parameter and optimisation simulations. Model courtesy of BTicino SpA, Italy. Read full article..

Analysis of a high efficiency reflector feed array

Analysis of a high efficiency reflector feed array
This article demonstrates the application of CST MICROWAVE STUDIO® (CST MWS) to the analysis of large reflector feed arrays. An array consisting of 19 elements was simulated but a larger array of more than 100 elements may also be simulated since the memory scaling with mesh cells in CST MWS is almost linear. The simultaneous excitation feature in CST MWS was applied to obtain farfield patterns in just a single simulation. A parameter sweep was also carried out to obtain the S-Parameters as a funtion of element feeding postion. Read full article..

Embedded Dual-Band GSM Antenna Design

Embedded Dual-Band GSM Antenna Design Document type
This application note illustrates how CST MICROWAVE STUDIO® (CST MWS), Antenna Magus and Optenni Lab can be used in combination to improve an existing GSM tracking device application. The requirement was to replace an existing “off-the-shelf” antenna on a GSM tracking device with an embedded, integrated antenna in order to reduce manufacturing and component costs. The new antenna had to operate inside the standard GSM 900 and 1800 frequency bands and had to use the existing substrate and metallic layers, without changing the existing circuit layout or the size of the PCB. The new integrated antenna was designed using Antenna Magus in combination with CST MWS to account for unwanted coupling, ensuring that the antenna operated within the desired frequency bands. Read full article..

Magnetostatic simulation of a magnetic injection valve

Magnetostatic simulation of a magnetic injection valve
CST EM STUDIO™ (CST EMS) is applied to the simulation of a magnetic injection valve by use of its non-linear magnetostatic solver. The aim of the simulation is to obtain the force on the valve armature as a function of the air gap between the armature and the main valve housing. Using the powerful and easy-to-use parameterisation features in CST EMS, a familly of force curves as functions of gap and excitation current can be easily generated. Read full article..
Back Back  

Your session has expired. Redirecting you to the login page...